Behavior of female and male mice submitted to action of p-chlorophenylalanine in prenatal ontogenesis

Effect of serotonin (5-HT) deficit produced by administration ofp-chlorophenylalanine at a dose of 400 mg/kg to pregnant female mice on the day 8 of gestation and on the subsequent behavior of their offspring (hybrids F1 (C57BL/CBA)) was studied. The 5-HT deficit in prenatal ontogenesis leads to the following changes of behavior: 1) females and males of the experimental group show a higher level of the explorative activity in the "open field" than control animals; 2) in females of the experimental group at the age of 90 days, unlike control females and males of experimental and control groups, the explorative activity is extinguished at the threefold testing in the "open field"; 3) females of the experimental group have a decreased level of anxiety in tests "elevated plus-maze" and the "dark-light chamber". Males of the experimental group, on the contrary, have an elevated level of anxiety. The obtained data show that the 5-HT deficit at the prenatal period affects various aspects of behavior. The degree of the changes produced by the prenatal 5-HT deficit can have different manifestation depending on sex of the animals.     

Behavior of male and female mice submitted to action of <Emphasis Type="Italic">p</Emphasis>-chlorophenylalanine in prenatal ontogenesis

Effect of serotonin (5-HT) deficit produced by administration of p-chlorophenylalanine at a dose of 400 mg/kg to pregnant female mice at the 8th day of gestation on the subsequent behavior of their offspring (hybrids F1(C57BL/CBA)) was studied. The 5-HT deficit in prenatal ontogenesis leads to the following behavioral changes: (1) females and males of the experimental group have a higher level of the explorative activity in the “open field” than control animals; (2) in females of the experimental group at the age of 90 days, unlike control females and males of experimental and control groups, the explorative activity is extinguished at the threefold testing in the “open field”; (3) females of the experimental group have a decreased level of anxiety in tests “elevated plus-maze” and the “dark-light” chamber. Males of the experimental group, on the contrary, have an elevated level of anxiety. The obtained data show that the 5-HT deficit at the prenatal period affects various aspects of behavior. The degree of the changes produced by the prenatal 5-HT deficit can have different manifestations depending on sex of the animals.     

The influence of intracysternal insulin administration on the rat temporal behaviour dynamics

Rat behaviour in the open field and elevated plus-maze was analyzed in rats after intracysternal administration of 2.5, 25, 50 and 200 ng of insulin in 45 min, 24 hrs and on the 9th day after single injection. Dose-dependent changes in 45 min occurred in both behavioural tests: insulin in low doses (2.5 and 25 ng) increased probability of locomotion and investigative activity in open field, while insulin in high doses (50 and 200 ng) did not alter locomotor activity and showed tendency to weakening of the investigative behavior (especially in the dose of 50 ng). Tendency was found in 24 hrs to increase probability of investigative behavior in open field after injection of 25 ng of insulin, although on the 9th day after insulin administration this behaviour increased in all experimental groups for all used doses. Insulin in the doses 2.5 and 200 ng decreased anxiety in elevated plus-maze in 45 min during the first five min; the doses 2.5 and 25 ng at the second five min exerted the same effect. In 24 hrs, the anxiety level increased for the doses 50 and 200 ng, and there was a tendency for an increase in the doses 2.5 and 25 ng; anxiety was decreased on the 9th day for all used doses of insulin. Thus, single insulin administration induced weakness of non-associative memory in open field on the day 2 and day 9 as well as increase of anxiety level on the day 2 and decrease of anxiety level on the day 9 in elevated plus-maze.     

Pharmacological studies on the anxiolytic effect of standardized Schisandra lignans extract on restraint-stressed mice

Fruits of Fructus Schisandrae were used as sedatives and hypnotics in traditional Chinese medicine for a long history. In this study, we investigated the effects of schisandra lignans extract (SLE) on anxiety disorder in restraint-stressed mice using light-dark (L-D) test. The influences of restraint stress on the levels of monoamines: noradrenaline (NE), dopamine (DA) and serotonin (5-HT) in cerebral cortex, as well as plasma corticosterone (CORT) were studied in mice. The HPLC fingerprint of SLE was recorded and the percentage composition of Schisandra lignans was determined as 82.63%. In L-D test, it was found out that 18 h of restraint stress significantly decreased the anxiolytic parameters (explorative behaviors, e.g. number of entries, time spent) in light area indicating high state of anxiety in stressed mice. In addition, restraint stress elevated NE, DA, and 5-HT levels in cerebral cortex of anxiety mice. Plasma CORT level was also increased. Oral administration of SLE (100 and 200 mg/kg/day, 8 days) emolliating the level of stress-induced anxiety by significantly increasing the anxiolytic parameters mentioned above. We also observed decreases in cerebral cortex monoamines levels, as well as plasma CORT level in stressed mice. These results suggested that SLE reversed stress-induced anxiety level, changes of cortex monoamine transmitters and plasma CORT. The anxiolytic effects of SLE might be related to its anti-stress activity by modulation of hyperactive HPA axis.     

Neuroprotective effects of semax in MPTP-induced disturbances of brain dopamine system

Effects of an ACTH (4-10) analogue Semax (MEHFPGP) on behaviour of white rats with MPTP-induced disturbances of brain DA-system have been studied. It was shown that MPTP administration (25 mg/kg) reduced motor activity and auhmented the anxiety level in rats. Semax administration (daily intranasal 0.2 mg/kg) attenuated behaviour disturbances induced by neurotoxin. The observed protective action of Semax in rats with MFTP-induced DA system disturbances may be due to both its modulating influence on the brain DA system and peptide neuroprotective effects.     

Open field behavior and habituation in rats irradiated on the head with gamma-rays

The goal of this work was to establish the effects of irradiation of the head with gamma-rays on selected forms of innate behavior, as well as on the habituation process to new environment in the open field test in rats. During a 5-day control period behavioral parameters reflecting motoric and explorative activities, as well as anxiety (6 parameters in total) were followed daily in 20 male Sprague-Dawley rats in an open field. Fourteen animals were repeatedly tested after irradiation of the head with a single dose of 10 Gy of gamma-rays. The results showed statistically significant depression of motoric and explorative activities during the first 3 days after irradiation in comparison with the control period. After irradiation the level of anxiety was elevated. Habituation to a new environment was observed in non-irradiated, but not in irradiated animals. These results suggest that the applied dose of ionizing radiation influenced the brain centers involved in control of innate behavioral functions connected with response to a new environment in rats.     

Singing Activity Reveals Personality Traits in Great Tits

In animal communication, sexually selected signals have been shown to often signal individual attributes such as motivation or quality. Birdsong is among the best studied signalling systems, and song traits vary substantially among individuals. The question remains if variation in signalling also reflects more general and consistent individual characteristics. Such consistent individual differences in behaviour that are relatively stable over time and contexts are referred to as personality or behavioural syndromes. Here, we studied the relation between singing and explorative behaviour, a well‐studied personality trait, using great tits (Parus major) under standardized aviary conditions. The results show that singing activity measured as the number of songs sung in spring prior to breeding correlated with male but not with female explorative behaviour. In contrast, song repertoire was not related to explorative behaviour but varied over the day. The link between explorative and singing behaviour suggests that sexually selected signals are more than signals of quality but can also reflect other intrinsic behavioural characteristics such as personality traits.     

Effects of personality on territory defence in communication networks: a playback experiment with radio-tagged great tits

Individuals often differ consistently in behaviour across time and contexts, and such consistent behavioural differences are commonly described as personality. Personality can play a central role in social behaviour both in dyadic interactions and in social networks. We investigated whether explorative behaviour, as proxy of personality of territorial male great tits (Parus major), predicts their own and their neighbours'' territorial responses towards simulated intruders. Several weeks prior to playback, subjects were taken from the wild to test their exploratory behaviour in a standard context in the laboratory. Exploratory behaviour provides a proxy of personality along a slow–fast explorer continuum. Upon release, males were radio-tracked and subsequently exposed to interactive playback simulating a more or a less aggressive territorial intruder (by either overlapping or alternating broadcast songs with the subjects'' songs). At the same time, we radio-tracked a neighbour of the playback subject. Male vocal responses during playback and spatial movements after playback varied according to male explorative behaviour and playback treatment. Males with lower exploration scores approached the loudspeaker less, and sang more songs, shorter songs and songs with slower element rates than did males with higher exploration scores. Moreover, neighbour responses were related to the explorative behaviour of the subject receiving the playback but not to their own explorative behaviour. Our overall findings reveal for the first time how personality traits affect resource defence within a communication network providing new insights on the cause of variation in resource defence behaviour.     

Effects of chronic Semax administration on exploratory activity and emotional reaction in white rats

Effects of chronic intranasal administration of ACTH(4-10) analog Semax (MEHFPGP) on exploratory activity, anxiety level, and depression-like behaviour were studied in white rats. The peptide was injected daily in dose 0.05 mg/kg during 10 or 14 days. It was shown that chronic Semax administration at 1-2 weeks induced anxiolytic and antidepressant effects but did not influenced the exploratory activity in non-stressogenic environment. The Semax effects may be the results of activation of the brain serotoninergic system as well as increased BDNF expression in the rat hippocampus.     

Increased exposure to predators increases both exploration and activity level in Brachyrhaphis episcopi

Two temperament traits, tendency to explore and activity level, were measured in a tropical poeciliid fish, the Panamanian bishop Brachyrhaphis episcopi. Open-field arena tests were used to quantify how predation pressure shapes activity levels and exploratory behaviours. Fish behaviour differed between high and low-predation populations. Fish that experienced higher levels of predation were both more explorative and more active. There were also some individual differences within populations; fish varied in their levels of exploration and activity in a novel open arena, but these differences were not related to sex or size. Together with previous studies on this species, these results indicate that there is a behavioural syndrome associated with predation pressure. Fish from high-predation populations are bolder, more explorative and more active than those from low-predation populations.     

Explorative behaviour is not associated with metabolism in the European Pied Flycatcher Ficedula hypoleuca

The pace‐of‐life syndrome hypothesis (POLS) represents an attractive theoretical framework suggesting that physiological and behavioural traits have evolved together with environmental conditions and life‐history strategies. POLS predicts that metabolic differences covary with behavioural variation such that high metabolic rate is associated with risk‐prone behaviour and a faster pace‐of‐life, whereas a low metabolic rate is associated with risk‐averse behaviour and a slower pace‐of‐life. We tested the POLS hypothesis in captive European Pied Flycatchers during their first year by examining the relationship between explorative behaviour and basal metabolic rate. Our results are inconsistent with POLS. The positive association of explorative behaviour with basal metabolic rate was not recovered for either sex, possibly due to foraging conditions in the aviaries where control and trial groups were fed twice a day, the birds' young age, developmental plasticity, or a non‐existent syndrome.     

Colony size,nestmate density and social history shape behavioural variation in Formica fusca colonies

In ants, individuals live in tightly integrated units (colonies) and work collectively for its success. In such groups, stable intraspecific variation in behaviour within or across contexts (personality) can occur at two levels: individuals and colonies. This paper examines how colony size and nestmate density influence the collective exploratory behaviour of Formica fusca (Hymenoptera: Formicidae), in the laboratory. The housing conditions of the colonies were manipulated to vary the size of colonies and their densities under a fully factorial design. The results demonstrate the presence of colony behavioural repeatability in this species, and contrary to our expectations, colonies were more explorative on average when they were kept at lower nestmate densities. We also found that experimental colonies created from larger source colonies were more explorative, which conveys that a thorough understanding of the contemporary behaviour of a colony may require knowing its social history and how it was formed. Our results also convey that the colony size and nestmate density can have significant effects on the exploratory behaviour of ant colonies.     

The effect of glyprolines on stressogenic disorders in the rat behaviour

Protective and antistress effects of three glyprolines--PGP, PG and GP, were studied. Stress influences produced typical changes of behavioural activity of rats in the elevated pluz-maze and the hole-board tests. These changes suggest a significant enhancement of anxiety and a drop of the level of orientation-investigative activity. A preliminary (15 minutes before stress agent) intraperitoneal administration of PGP or GP in doses of 3.7 microm/kg significantly decreased stress disturbances of behaviour. Analysis of these data shows to the possibility of PGP and GP influences on the CNS structures, which take part in the organism reciprocal reactions to stress factor. The peptide GP at equimolar dose didn't possess pronounced protective properties and just slightly decreased stress disturbance of behavioural activity of rats.     

VEGF and Notch Signaling

Tubular sprouting in angiogenesis relies on division of labour between the endothelial tip cell, leading and guiding the sprout and their neighbouring stalk cells, which divide and form the vascular lumen. We previously learned how the graded extracellular distribution of heparin-binding Vascular Endothelial Growth Factor (VEGF)-A orchestrates and balances tip and stalk cell behaviour. Recent data now provided insight into the regulation of tip cell numbers, illustrating how Delta-like (Dll)4 – Notch signalling functions to limit the explorative tip cell behaviour induced by VEGF-A. These data also provided a first answer to the question why not all endothelial cells stimulated by VEGF-A turn into tip cells. Here we review this new model and discuss how VEGF-A and Dll4/Notch signalling may interact dynamically at cellular level to control vascular patterning.     

Changes in the animal behavior caused by sequential changes of dominants related to reproduction

Female rats during the sex dominanta (proestrus) revealed lower anxiety scores and a higher general level of activity than the rats in diestrus. Responses to stress were also more obvious in proestrus. During gestation the rats revealed a lower activity and a higher anxiety. In lactation, the rats' behaviour was similar to that in proestrus.     

Risk Perception and Risk-Taking Behaviour during Adolescence: The Influence of Personality and Gender

This study investigated the influence of personality characteristics and gender on adolescents’ perception of risk and their risk-taking behaviour. Male and female participants (157 females: 116 males, aged 13–20) completed self-report measures on risk perception, risk-taking and personality. Male participants perceived behaviours as less risky, reportedly took more risks, were less sensitive to negative outcomes and less socially anxious than female participants. Path analysis identified a model in which age, behavioural inhibition and impulsiveness directly influenced risk perception, while age, social anxiety, impulsiveness, sensitivity to reward, behavioural inhibition and risk perception itself were directly or indirectly associated with risk-taking behaviour. Age and behavioural inhibition had direct relationships with social anxiety, and reward sensitivity was associated with impulsiveness. The model was representative for the whole sample and male and female groups separately. The observed relationship between age and social anxiety and the influence this may have on risk-taking behaviour could be key for reducing adolescent risk-taking behaviour. Even though adolescents may understand the riskiness of their behaviour and estimate their vulnerability to risk at a similar level to adults, factors such as anxiety regarding social situations, sensitivity to reward and impulsiveness may exert their influence and make these individuals prone to taking risks. If these associations are proven causal, these factors are, and will continue to be, important targets in prevention and intervention efforts.     

Reproduction of passive avoidance reactions after neurotensin microinjection into nucleus accumbens of rat brain against the background of reserpine action

The purpose of the study was to reveal the features of the influence of neurotensin injected into the nucleus accumbens on behaviour of rats after systemic administration of reserpine in the dose of 2 mg/kg. Reprodution of passive avoidance conditioned reactions, painful stimulation aftereffects on locomotor activity in the "open field", and behavior in the elevated plus-maze were studied. It was shown that reserpine administration impaired the reproduction of passive avoidance reactions and weakened the oppressing aftereffect of painful stimulation, which can be due to a decrease in anxiety in rats. Neurotensin prevented disorders in the defensive behavior evoked by reserpine and intensified the state of anxiety in the elevated plus-maze. The positive influence ofneurotensin on the reproduction of passive avoidance can be associated with the recovery of the anxiogenic effect of painful stimulation destroyed by reserpine. Thus, neurotensin injected into the nucleus accumbens could normalize the balance of brain monoaminergic systems.     

Influence of semax on the emotional state of white rats in the norm and against the background of cholecystokinin-tetrapeptide action

The effects of the adrenocorticotropic hormone (ACTH(4–10)) analog, Semax (MEHFPGP), on the level of anxiety and depression in white rats have been studied in the normal state and against the back-ground of cholecystokinin-tetrapeptide (CCK-4) action. Semax was injected intranasally in doses of 50 and 500 μg/kg 15 min before the testing. CCK-4 was administered intraperitoneally in a dose of 400 μg/kg 40 min before the testing. The level of anxiety was estimated in the elevated plus-maze test, and the degree of depression, in the forced swimming test. Semax administration did not influence the emotional state of animals in the normal state. The CCK-4 injection led to an increase in anxiety and depression in rats. Semax normalized the animal behavior disturbed by the CCK-4 administration, which attests to its anxiolytic and antidepressant effects at elevated levels of anxiety and depression.     

Exploration and ecology in Darwin’s finches

One of the main functions of exploratory behaviour is to gain information about the environment. The adaptive value of such behaviour should vary with ecological conditions influencing the diversity and stability of resources, as well as with the costs associated with gathering information. Consequently, predictions can be made about environmental factors influencing the evolution of exploration. We used comparative methods, combining a field experiment with literature data, to study correlated evolution between explorative behaviour and ecology among 13 species of Darwin’s finches. Controlling for phylogenetic influences, we found that exploration (measured as the proportion of individuals responding in the experiment) increased with diet diversity and the amount of fruit in diet, consistent with theories stating that exploration aimed at finding new food types should be more beneficial for generalists than for specialists. However, our study is the first to demonstrate a correlation between neophilia and food diversity. Contrary to our prediction, species with a high percentage of concealed food in their diet were less explorative. A possible explanation for this novel finding is that in our study system concealed food may be a stable resource, and species using such resources should be less dependent on the discovery of new food types.     

The dehydroepiandrosterone sulfate influence on anxiety and depressive behaviour: participation of mu-opioid receptors

The dehydroepiandrosterone sulfate (DHEAS) influence on anxiety and depressive behaviour was studied in animals after chronic stress exposures. It is shown that DHEAS (30 mg/kg) reduced anxiety in submission (with increased level of stress-induced anxiety resulting from chronic (20-days) defeats in aggressive interactions) of male mice of CBA/Lac strain in the "partition" test and in the plus-maze test, whereas in the control--only in the plus-maze test. DHEAS injection (30 mg/kg) in male Wistar rats decreased depressive behaviour in the Porsolt test in control and multiple (shuttling on the laboratory scrambler for 18 days by 1 hour in day) stressed animals. NaItrexone (0.25 mg/kg in mice and 0.1 mg/kg in rats) blocked anxiolytic and antidepressant-like effects of DHEAS. The findings suggest that these DHEAS effects are mediated by mu-opioid receptors.